Removing Algae on concrete wall

We have a build up of algae on the concrete wall surrounding our garden. As we have recently painted the outside the house and replaced the driveway the wall is looking even worse. These is also a hedge just inside the wall and the pavement outside.

Anybody got any ideas how to remove this gunk as we may paint it later

Blacksheep, You could also give Jeyes Fluid a go, try a patch to see
if it starts to take it off and then you know where you are going.
I hate the look of it on the wall and it makes everywhere else
look terrible - good luck with the work.

Hi Blacksheep, I had a problem with algae also, With a patio not a wall and I tried different options, I would try the bleach option first , The thicker the bleach the better, If that does not work then the jeyes fluid might, Sophie and Greengrass are offering the correct advice, But if all else fails The only thing that worked for me was a product called moss-go, You can get one for moss or algae,The bigger stores like md o, sheas, woodies or b and q should stock this, It is not the cheapest one on the market but it is well worth the 40.00 euro I paid for it, You dilute it 1 part moss go (Moss go algae in your case) and 4 parts water and apply with your average watering can, You might need a ladder to do this in your case, You can only apply if we are due dry weather for 24 hours as it needs to set in and then let nature take its course By that I mean the rain will wash it off for you, If it is very bad use a bucket and a hard brush to apply, Again the rain will do the rest, Best of luck.

Glad to be able to add my input 'Black Sheep' as you have helped me and so many others, and hopefully will continue to in the future, with your sound advice and experience in the past.

I have used MossGo and Hyperchlorine in the past to do the job you require and to be honest I have not had success with either. I find the power hose to be the most effective job with a flat spray of water. Make sure that the pressure is not too severe and start with a lower setting and work up. Also, keep the lance back from the wall initially and move closer if needed.